Field of the Invention
The present invention relates to a backlight unit and a display device including the same. More specifically, the present invention relates to a backlight unit and a display device including the same to stably fix a light guide plate.
Discussion of the Related Art
Flat display devices such as liquid crystal display devices and organic light emitting display devices are widely used due to advantages such as low driving voltage, slimness, and superior image quality.
Among the flat display devices, the liquid crystal display device includes a liquid crystal panel for controlling transmittance, a backlight unit disposed at the back or side surface of the liquid crystal panel for emitting light, and a case for accommodating the liquid crystal panel and the backlight unit. The case includes a cover bottom serving as a lower cover of the backlight unit. The backlight unit includes a light source, a light guide plate, a reflective sheet, and an optical sheet, which are accommodated in the cover bottom. In addition, the cover bottom is bonded to the liquid crystal panel by a front case paired with the cover bottom to form a liquid crystal module.
However, the liquid crystal display device has a white spot problem wherein light blurs in a partially damaged part of the light guide plate. The white spot is due to an increase in light scattering in a part of the light guide plate that results from scratches on a part of the light guide plate or the reflective sheet, or from breakage of beads formed on the light guide plate or the reflective sheet. The white spot causes deterioration in display quality of display devices.
For example, the liquid crystal display device generally utilizes an edge-type backlight unit in which a light source disposed on a side surface of the light guide plate is accommodated in the cover bottom in order to reduce the thickness of the display device. The edge-type backlight unit has a configuration in which a reflective sheet is staked on an inner surface of the cover bottom, a light guide plate is disposed on the reflective sheet, and a side surface of the light guide plate is surrounded by a side surface of the cover bottom. The side surface of the light guide plate, the side surface of the cover bottom, and the side surface of the light guide plate are spaced from one another by a predetermined distance in consideration of expansion and contraction of the light guide plate and are not in contact with one another.
The distance allows for displacement of the light guide plate in the cover bottom and thereby causes scratches on the surface of the light guide plate or the reflective sheet when physical force, such as an impact causing displacement of the light guide plate, is generated during use of the display device or transport of the display device.